Preparation of paraffin wax for utilizing its thermal expansion properties



July 6, 1965 l A. R. RONZIO ETAL PREPARATION OF PARAFFIN WAX FORUTILIZING ITS THERMAL EXPANSION PROPERTIES Filed NOV. 25, 1960 5Sheets-Sheet 1 AIR CONDENSER TO VAC.

VIGREAUX COLUMN FRACTION COLLECTOR l0 l2 14 PERCENT EXP F/ .30.

0 min...

TO CONDENSER HEATER m T W VR N w y 6, 1965 A. R. RONZIO ETAL 3,193,600

PREPARATION OF PARAFFIN WAX FOR UTILIZING ITS THERMAL EXPANSIONPROPERTIES Filed'Nov. 25, 1960 s Sheets-Sheet 2 TO PUMP TO VAC. \J

' a: l-Ll l- U1 2 l3 g 2 INVENTORS.

ANTHONY. R. ROIVZ/O JOHN E SHERWOOD ATTORNEY 6, 1965 A. R. RONZIO ETAL3,193,600

PREPARATION OF PARAFFIN WAX FOR UTILIZING ITS THERMAL EXPANSIONPROPERTIES Filed Nov. 25. 1960 3 Sheets-Sheet 5 VACUUM VACUUM A PUMP BM;36 l \I I, .35

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. -50 INVENTORS.

I 46 ANTHONY R. RO/VZ/O L JOHN E :SHERWOOD 5| 47 ATTOR/VE United StatesPatent 3 193 660 PREPARATION or PA RA FFIN wAx FOR UTILIZ- ING ITSTHERMAL EXPANSIGN PROPERTIES Anthony R. Ronzio, Littleton, and John F.Sherwood,

Golden, Colo.; said Ronzio assignor to Thermal Hydraulics, Inc., Denver,Colo, a corporation of Colorado Filed Nov. 25, 1960, Ser. No. 71,564 7Claims. (Cl. 264-102) This invention relates to preparation of paraffinwax for utilizing its thermal expansion properties. More particularly,the invention relates to the pre-treatment of parafiin wax for thepurpose of improving its capacity to impart motion to mechanisms byexpansion of the wax. The expansion properties of wax may also beutilized for the forming of metal products.

' Paraflin wax, pre-treated as hereinafter described, may be encased ina high pressure cylinder and heated to actuate reciprocating means inthe cylinder for operating dampers, valves, shutters, pumps and otherdevices.

The thermal expansion of commercial paraffin wax has been utilizedheretofore for imparting motion to mechanisms, such, for example, asshown in US. Patent No. 2,815,642, December 10, 1957, to John F.Sherwood. In efforts to increase the efiiciency of commercial paraffinwaxes for actuating mechanisms and for other purposes, such, forexample, as the forming of metal products, we have discovered that thecomposition of waxes can be altered and the thermal expansion propertiesof the waxes thereby substantially improved. I

By experiments which will be described hereinafter, we have determinedthat paraffin wax contains dissolved hydro-carbon gases and that moltenparaffin wax absorbs oxygen from the air. Further, we have ascertainedthat the presence of these gases in the paraffin wax heretofore used toactuate mechanism lessens the expansion and pressure producingcapacities of the wax when heated, and results in a gas cushion whichresists the return movement of the pressure actuated means.

Therefore an important object of the invention is to devise methods ofpreparing paraffin wax for utilizing its expansion properties bypr'e-t'reatment which frees contained gases and oxygen from the wax andprevents absorption of oxygen from the air by the degassed wax. When thewax, preheated as described herein, is sealed in a high pressurecylinder or mold and subjected to heat, it exhibits high expansion andpressure exerting capacities compared to commercial paraflin waxes. Whencooled, the wax produced by our invention contracts without formation ofgases. When sealed in a cylinder, the contraction of our pre-treated waxresults in a vacuum zone located axially of the cylinder whichfacilitates the return stroke of pressure actuated means in thecylinder.

The valves, dampers, shutters and other mechanisms referred to herein,which may be operatively connected to pistons or plungers actuated bythe thermal expansion of wax encased in a high pressure cylinder,usually are designed to function automatically in response tothermostatic controls at diiferent temperatures, sometimes within narrowranges of temperatures. Therefore the production of wax having thedesired melting point or range, as well as optimum expansion andcontraction properties, is another important object of our invention.

Parafiin wax is a mixture of hydrocarbon compounds belonging to threedistinct systems: the straight or long chain waxes, branched chain waxesand naphthenic waxes. The long chain paraiiins have higher meltingpoints than the branched chain, and the naphthenic paraffins have thelowest melting points for components having the same 3,193,5WPatentedJuly 6, 1965 Ice number of carbon atoms. The separation ofhydrocarbons for the purposes of this invention may be based on boilingpoint or on structure, i.e. the clatherate forming compounds which ingeneral, are long chain hydrocarbons.

The paraflin wax known commercially as Eskar-R40, for example, issuitable for treatment by our process, and therefore the experimentsdescribed herein were performed with respect to this wax.

The aforementioned and other objects and advantages of the inventionwill become apparent from the drawings and following specification.

In the drawings:

FIG. 1 shows diagrammatically a vacuum distillation apparatus used inExperiment 1.

FIGS. 2 and 3 show diagrammatically the apparatus employed in Experiment2.

FIG. 3-a is a graph showing volume increase of a wax sample at differenttemperatures.

FIGS. 4, 5, 6 and 7 show diagrammatically the appa ratus employed inExperiments 4, 5, 6 and 7, respectively.

FIG. 8 shows diagrammatically the steps of the method used to moldparaflin wax, pre-treated according to this invention, and to encase themolded wax in a high pressure cylinder for actuating a piston embeddedin the wax.

FIG. 9 is a plan view of the mold included in FIG. 8.

FIG. 10 is a vertical sectional view in the plane of the line 10-10 ofFIG. 9, on an enlarged scale.

FIG. 11 is a vertical sectional view showing the method of encasing themolded wax and parts embedded therein in a high pressure cylinder.

Experiment ].In order to study the behavior of narrow cut fractions of aselected paraffin wax, a vacuum fractional distillation of Eskar-R40 wasmade by the following procedure: A 200 g. sample was fractionallydistilled through a vacuum distillation apparatus shown in FIG. 1. Thestill pot was heated with an oil bath to obtain uniform and even heat.The oil bath temperature gradually rose during the course of thisdistillation from 230 C. to 265 C. As the heating progressed there was avigorous evolution of gas. The Vigreaux column was warmed with turns ofNich'rome wire which in turn Was controlled with a Variac transformer.

. The vacuum in the distillation apparatus was broken two times in orderto change distillate receivers. The distillation temperatures changed inboth instances even though the pot was allowed to cool to about C.before admitting air.

The fractions collected in Experiment 1 are shown in the following Table1:

Table 1 Range, Weight, MP Fraction No. 0. grams Range Remarks 13. 6153-56 29.21 54-555 14.64 55.5-56 22.92 55.5-57 21.30 57. 5-64 Vacuumbroken 0 ange receivers. 14.64 58.5-61 7. -200 32.36 59-63 8- 200-21028.92 61-65 9. 200-210 11.39 59-66 D0. 10 Residue Experiment 2.The rateof expansion of the Eskar- R40 wax in response to temperature changeswas deterquantitiative value to the amount of contraction.

areaeeo I paratus shown in FIGS. 2 and 3 was fabricated of Pyrex Thedialotometer, FIG. 2, was calibrated with The dried reservoir 10 wasfilled with wax to the glass. water. mark indicated by the arrow.

The tube was then attached to the vacuum system and the wax melted andcooled until completely degassed and no empty space was present Waterwas added to the reservoir to the feducial mark and the assembly thenattached to the apparatus as shown in FIGURE 3.

A series of determinations were made using the boiling point of solventsto maintain a constant temperature. Progress in the work showed it wasnecessary to deter-' mine points on the curve at'closer intervals.Mixtures of methylene chloride,'B.P. 40.1, and ethylene chloride,

13.1. 83.5 were therefore used. The data obtained is shown in the.following table.

Table 2 B .P., Volume Percent- No. degrees Time Increase age Remarks ml.Change 22 8.30 Room temperature. 36 9. 30 460 1. 6 I 40. 5 9. 50 280 2.5 45. O 10. 10 310 3. 6 51 10. 30 235 4. 4 54. 5 ll. 20 175 5. 55. 6 11.40 125 5. 6 58 12. 30 795 Began to melt discarded.

The data compiled in Table 2'together with data obtained by observingthe volume of liquid parafiin at the boiling points of'acetone, alcohol,water and toluene, was

used to plot the graph shown in FIG. 3'-a. As indicated by the graph,the results of this experiment showed that V a break occurs in the curveat 45 C., indicating a change of phase, but the change is minor. 7 Thesignificant change in volume occurs at the melting point of the waxwhich occurred within the range between 54-60 C. This 11% change involume is pronounced and indicates that as the purity of the wax isincreased, the range of melting can be reduced materially so'that thechange in volume will occur rather sharply.

Experiment 3.In order to determine the amount of contraction uponcooling in the various fractions of the wax, an experiment was conductedwith respect to Fractions 1, and 9 of Table 1. Samples of-the threefractions were placed in graduated tubes and weighed.

The tubes were then connected to the vacuum system. and Were melted byimmersing in boiling water. After 30 minutes the volume was read whilestill heated to 95.5".

Upon cooling, the wax samples solidified and contracted leaving a cavityin the center of the tube. This cavity was usually filled with asolidified foam of wax, indicating dissolved gases separated fromsolution when the wax solidified. The wax was again attached to thevacuum line and melted, then cooled. This was repeated until gas was nolonger given off upon cooling. As many as four cycles were necessary toattain this characteristic.

The tubes were then removed from the vacuum line and distilled water wasadded from'a buret to give a Suf- 4:. Fraction 9: V V

B.P. ZOO-210 C.; Wt.'1l.39 g. (5.69%)

Contraction found: 13.66%

It was noted in this experiment that gas was given off when the liquidwax solidified. This became apparent as a solid foam of small bubbles inthe center of the wax. Upon remelting the wax while under vacuum, thesebubbles roses to the surface and were removed by a pump. It was observedthat some of the bubbles decreased in size while rising in the liquid,indicating that some gas redissolved. Therefore it was necessary toeither repeat the melting-freezing process on the wax while undervacuum, or heat the wax to 150 C. The latter method caused considerablewax loss due to violent evolution of gas.

The data obtained from the experiments described with respect to meltingpoints and expansion and contraction rates in response to temperaturechanges, enable the user to select'the paraifin fraction suitable forembodiment in a given thermally controlled mechanism or for otherpurposes. 7

The next step of our process is the result of experiments whichindicate'that paraffin wax contains hydrodrocarbon gas is present in waxand is released at about v140" C., or under high vacuum at a temperatureof C.; that molten par'affin wax absorbs oxygen from the air and thatthe oxygen is released slowly when the wax is melted. Unless the waxemployed for thermal expansion is freed of gases before being encased,the gases will be released within the pressure cylinder when thecontained wax is subjected to heat in the normal operation of themechanisms. 7 7

Experiment 4.-This experiment was made to determine the kind ofgaspresent in paraffin wax. A quantity of shavings of Eskar-R140, 131.2 g.was placed in a flask and attached to a vacuum system, a diagram ofwhich is shown in FIGURE 4. The vacuum system used is capable of givingvery high vacua and includes both a mechanical and diffusion pump 11. 7

After a goodvacuum was established in the system, the

flasklz containing the wax was heated in a Water bath while trap 13 ofthe system was cooled with liquid nitrogen. The vacuum was applied aslong as gas was evolved by the wax. The system was then opened and flask12 was allowed to cool in air, and weighed when at room temperature. Theloss in weight was less than 0.1 g. which would correspond to less than0.08% dissolved gas. I The material frozen out with liquid nitrogen wasa mixture of condensed gases. As the tube, removed from the trap 13, wasallowed to warm the majority of the.

. material in the form of a white film was sublimed off and ficientwater was added to bring the reading equal to- V the volume the waxoccupied at the temperature of boiling water. j V

The contraction measured was that observed in going from 95 .5 C. (theboiling point of water) to room tern-- perature 22 C.

Fraction 1: V v

B.P. -175" C.; wt. 13.61 g. (6.80% of sample) Contraction found: 6.8%

Fraction 5':

7 HP. -195 C.; wt. 21.30 g. (10.65%)

Contraction found: 12.45%

a. sweetish odorofihydrocarbonwas present. 7 A very small portion, whenobserved with a magnifying glass, was in the form ofminute droplets.These also quickly evaporated 01f... The odor \of hydrocarbon gas wasstill present. A few milliliters of water was added and the cylinderwasshaken. A strip of universalpH paper was. added to the solution. Therewas no change in color, in-

insufficient 'tion of the hydrocarbon material:isolated becomes liquidbefore evaporating olf; and (c) any acid, if present, is insuflicient tochange the color of Hydrion pH paper.

Experiment 5.-An additional experiment was made to further evaluate theobservations made in Experiment 4.

(a) When 29.9965 g. of wax was placed in a tared flask, which wasattached to the vacuum system and heated with a water bath (95 C.),completely degassed, cooled and weighed again, while still under vacuum,a loss in weight was observed which amounted to 0.0060 g. (0.02%

(b) The wax was remelted and allowed to solidify in the open air. Theflask containing the wax was then attached to the vacuum system shown inFIGURE 5. After evacuation was complete, the pumps were closed off fromthe vacuum system and the flask containing the wax was heated with awater bath. Gas was given off. When evolution of gas ceased, the wax wasallowed to cool to room temperature and the system was allowed to standovernight. The system, after equilibrium was established showed apressure of mm. of gas pressure.

Experiment 5(a) indicates that the dissolved hydrocarbon gas amounts to0.02%.

Experiment 5 (b) indicates that molten wax will absorb a gas from airwhich is then given off at 95 C.

Experiment 6.To establish the nature of gases which are dissolved inparaflin, apparatus shown in FIG. 6 was fabricated and assembled.

A gentle stream of air was pulled through the apparatus with suction.This air vwas purified (CO removed) by tube 14 filled with Ascarite (aC0 absorbent). The gas was then led to the bottom of flask 15 whichcontained 200 g. of paraflin in the form of lumps. Flask 15 was immersedin a basin of cold water which could be heated with an electric heaterwhen desired. The gas was then led through tube 16 filled with glasswool. This serves to retain any spray or fine particles of wax entrainedin the gas stream. Then the gas was passed through tube 17 which wasalso filled with Ascarite. This tube will absorb any carbon dioxide gasgiven oh by the wax. The gas stream was then passed through a quartztube 18 which contained a filling of copper oxide which was heated tored heat with burner 19.

At red heat copper oxide, CuO, reacts with hydrocarbon gases to givecarbon dioxide and water. Using ethane as an example of the gas we wouldthen have the equation: CH CH +7CuO+7Cu+2CO +3H Q The oxygen in the airwould then combine with the hot copper to regenerate copper oxide.

The gas was then passed through a saturated solution of barium hydroxidecontained in flask 20. This reagent will react with carbon dioxide togive insoluble barium carbonate according to the following equation:

Tube 21 is a guard tube filled with Ascarite and serves to remove the C8from the air should the gas stream be blocked in some manner and avacuum appear in the system causing outside air to be drawn into flask20.

All rubber stoppers and rubber tubing were boiled in 10% caustic, washedwith distilled water and dried at 100" C. before use to remove anyorganic and inorganic volatile material which might nullify the results.

The assembly was purged by drawing air through the equipment at the samerate to be used later in the experiment. After minutes only a veryslight cloudiness appeared in flask 20.

The contents of flask 20 were then replaced with fresh barium hydroxidesolution while the flask 15 was warmed with boiling water to melt thewax. Air was pulled through the melted wax for 1 hour at a rate of 3bubbles/ sec. No cloudiness appeared in flask 20 indicating nohydrocarbon was being evolved.

The water bath surrounding flask 15 was removed and the flask was heateddirectly with the electric heater.

At about C. cloudiness began to appear in flask 20, indicating ahydrocarbon was being freed by the paraffin. This evoluation of gas wasmore rapid above this temperature. Heating was terminated after 30minutes of heating.

The apparatus shown in FIGURE 7 was then assembled and used in thisexperiment. Nitrogen from a compressed gas cylinder attached to aregulator was led into wash bottle 22. Fine regulation of the gas streamwas made with screw clamp 23. Wash bottle 22 contained about 200 ml. ofa strong potassium pyrogallate solution (PPG). This solution reacts withoxygen and serves at this point to absorb all trace of oxygen in thestream of nitrogen. The gas stream then is led to the bottom of flask 24which contained 200 g. of paraflin in the form of lumps. The stream ofnitrogen was then led into wash bottle 25 which also containedpyrogallate. Wash bottle 26 contained water only and served as a guardbottle to keep air from bottle 25.

The apparatus was purged for 30 minutes with a flow of nitrogen gas. Atrace of oxygen was removed from the nitrogen indicated by a slightdarkening of color. The solution in 25 was replaced with fresh solution.After 30 minutes solution in 25 was almost black indicating much oxygenwas present.

The wax was then melted by heating the water around the flask 24 withthe heater. A fast stream of nitrogen was then used to purge the system(20 minutes). The pyrogallate in 25 was replaced with fresh solutionandthe experiment was continued. The solution turned black in 10 minutes.

This experiment indicate that wax degassed under vacuum absorbs oxygenfrom air when allowed to cool in air, and that the oxygen is releasedslowly when the wax is melted.

Therefore, after selection of a suitable wax, the next step of ourprocess is to free the wax of dissolved hydro carbon gas and oxygen bypre-heating the wax, and, following the degassing procedure, to preventabsorption by the wax of oxygen from the air by maintaining the degassedwax under vacuum. The temperature at which the wax is degassed beforebeing encased in a sealed cylinder depends on the conditions under whichthe thermally controlled unit is intended to operate, as more fullyexplained hereinafter. Before encasing the pro-treated wax in a sealedcylinder, we maintain the degassed wax in molten state under vacuumbefore and during a molding operation. Preferably we embed a pistontogether with an electrical filament holder and filament wound thereonin the molten degassed wax under vacuum. This is done by first placingthe piston and filament holder with filament wound thereon in a mold andpouring the molten pre-treated wax into the mold under vacuum to coverand embed the said parts and to completely fill the mold cavity. Thepiston and filament holder with filament thereon may be of theconstruction shown in the copending application of John F. Sherwood,Serial No. 51,110, for Thermally Controlled Expansible Means forImparting Motion to Mechanism.

FIG. 8 shows diagrammatically a reservoir 39 contain ing degassed moltenwax under vacuum, pre-treated in accordance with this invention, avalved conduit 31 for conveying the wax under vacuum to a two part mold32 and vacuum producing means. The mold 32, as shown in FIGS. 9 and 10,is provided with four cavities 33 communicating with awax distributionchamber 34 into which wax is fed by the conduit 31. Any desired numberof cavities 33 may be provided. f

An electrical filament holder 35 with filament 3'6 wound thereon isplaced in each cavity 33. An electrical condoctor 37 extends from thefilament 36 into the connector 38 which protrudes beyond the bottom ofthe lower mold part 39. The upper mold part 4% is provided with sealedopenings through which extend pistons 41 to be embedded in the wax ineach cavity 33. For clarity, one piston 41 is shown in lowered, embeddedposition while another is shown in raised position in FIG. 10, but itwill be understood that the molten pro-treated wax is forced into thecavities 33 from the distribution chamber 34-by the pressure piston 42therein to completely fill the cavities 33 while the pistons 41 are inraised positions. Whenthe wax has cooled, the pistons 41 are forceddownwardly into the wax filled cavities whereby the wax is compressed.All the foregoing steps are performed while the wax is maintained undervacuum. When the wax has solidified in each cavity 33 there has beenformed a cylindrical wax unit which includes the embedded filamentholder 35 with filament 36 wound thereon, the conductor 37 and connector33, and also the piston 41 partially protruding from one end of theunit. The adjustable bleeder valves 43 permit passage of air out of themold cavities as they become filled with wax under vacuum. i

The cylindrical wax units indicated as a whole at 44 are removed fromthe mold 32, ready for insertion in high pressure cylinders such as theone indicated at 45, sup ported in die 46 of FIG. 11, which is drawn ona slightly 7 larger scale than FIG. 10. The insertion of each unit 44into a cylinder 55 is performed with the aid of vacuum 47 to draw theunit 44 by suction into the cylinder 4-5 and establish vacuum in thecylinder. The wax unit 44 then includes the parts embedded therein,together with the conductor 37, connector 38, and the opposite end plate48. When the unit 44 is in place, the reduced diameter portion 49 of thewax and the protruding end of the piston 41 fit in the cylinder portion2 and bear against the rubber pad 51 in the bottom of the die 46. Theend plate 48 fit's'in the cylinder 45 and when sealed thereon, closesthe cylinder at that end. a

Reverting now to the pre-treatment of the selected wax for the purposeof degassing the wax'before encasement in a high pressure cylinder, suchfor exampleas the cylinder 45 shown in FIG. 11, and preventing formationof gases under normal operating conditions'to which the thermallycontrolled unit may be subjected, we have noted that'dissolved gases arefreed'from the wax by pro-heating to approximately 140 C., or, underhigh vacuum to. approximately 95 C, and that if the unit is required tooperate under conditions where the temperature in the high pressurecylinder 4-5 does not exceed 95 C., the wax functions efiiciently byexpansion to impart required motion to the piston 41, and contracts whencooled without giving off gases.

However, when the thermal units are required to operate undertemperature and load conditions which create much higher temperatures inthe high pressure cylinders 45, it is necessary to preheat the wax totemperatures above the predetermined operating temperatures of the unitsto free dissolved gases which otherwise would be given off at saidoperating temperatures in the cylinders, and then to maintain thedegassed wax under vacuum until it has been molded and solidified forinsertion in the cylinders 45. V

It is known in the art of isolating wax frompetroleum, that chlorinatedhydrocarbons are employed in the purification processes and thatsmallfractions of the halogenated hydrocarbons used in industry may be foundin the isolated wax. Such halogenated hydrocarbons are freed at the sametemperatures heretofore stated for evolving hydrocarbon gases and oxygenfrom wax by our method. V t

The mechanisms herein shown and described in connectionwith our methodof preparing wax for utilizing its thermal expansion properties are forexemplary purposes only. The molten pre-treated wax may be molded undervacuum into solid units of various forms other than the specific shapeillustrated herein FIGS. 10 and 11, with or without embedding theheating elements and pistons therein.

We claim:

i. The method of preparing wax for improving its expansion andcontraction properties and capacity to impart motion to mechanism byexpansion of the wax when encased in a high pressure casing which issubsequently subjcctedto temperature exceeding the melting point of thewax for the purpose of expanding the encased wax, which comprisespro-heating the wax before encasement to temperature exceeding themelting point of the wax and exceeding the minimum temperature requiredto evolve hydrocarbon gases and oxygen from the wax and thereby freeingdissolved hydrocarbon gases and oxygen from the wax, maintaining thedegassed molten wax under vacuum and preventing absorption of oxygen,and molding the molten degassed wax under vacuum into solidified units,thereby preventing giving off of gases after encasement when the encasedwax is heated and contracts by cooling. f

2. The method defined by claim 1, in which the wax is pre-hea-ted to atemperature of at least 140 C.

3. The method defined by claim 1, in which the wax is pro-heated to atemperature of at least 95 C. under high vacuum. 7

4. The method of preparing parafiin wax for improving its expansion andcontraction properties and capacity to impart motion to mechanism byexpansion of the wax when encased in a high pressure casing whichsubsequently is subjected to temperature exceeding the melting point ofthe wax 'for the purpose of expanding the encased wax, which comprisesselecting a fraction of the wax having melting points in the 5460 C.range, pro-heating the wax before encasement to temperature exceedingthe melting point of the wax and exceeding the minimum temperaturerequired to evolve hydrocarbon'gases and oxygen from'the wax and therebyfreeing dissolved by drocarbon gases and oxygen from the wax,maintaining the degassed molten wax under vacuum and preventingabsorption of oxygen, and molding the molten degassed wax under vacuuminto solidified units, thereby preventing giving all of gases afterencasement when the encased wax is heated'and contracts by cooling.

5. The method defined by claim 4, in which the wax is pro-heated to atemperature of at least 140 C.

6. The method defined by claim d, in which the wax is pro-heated to atemperature of at least 95 C. under high vacuum.

'7. The method of preparing parafiin wax for improving its expansion andcontraction properties and capacity point of the wax for the purpose ofexpanding the encased wax, which comprises prc-heatingthe wax beforeencasement to temperature exceeding the meltingpoint of the wax andexceeding the minimum temperature required to evolve hydrocarbon gasesand oxygen from the wax and thereby freeing dissolved hydrocarbon gasesand oxygen from the wax, maintaining the degassed molten wax undervacuum and preventing absorption of oxygen, passing the molten degassedwax under vacuum into a mold cavity which contains an electrical heatingunit and a piston, filling the entire cavity with the wax and embeddingsaid heating unit and piston, allowing the wax to solidify under vacuum,thereby preventing giving oif of gases after encasement when theencased'wax is heated and contracts 9 by cooling, removing the moldedWax and parts embedded 2,477,273 therein and encasing the molded unit ina high pressure 2,815,035 cylinder. 2,815,642 2,846,599

References Cited by the Examiner 5 UNITED STATES PATENTS 1,394,034 10/21McVickar.

1,652,212 12/27 Priess 1859X 2,461,723 2/ 49 Cowan. 0

Tognola 1859 Eskin et a1. 60-23 Sherwood 6023 McAdam 18-59 X RGBERT F.WHITE, Primary Examiner.

WILLIAM J. STEPHENSON, MICHAEL V. BRINDISI,

MORRIS LIEBMAN, ALEXANDER H. BROD- MERKEL, Examiners.

1. THE METHOD OF PREPARING WAX FOR IMPROVING ITS EXPANSION ANDCONTRACTION PROPERTIES AND CAPACITY TO IMPART MOTION TO MECHANISM BYEXPANSION OF THE WAX WHEN ENCASED IN A HIGH PRESSURE CASING WHICH ISSUBSEQUENTYLY SUBJECTED TO TEMPERATURE EXCEEDING THE MELTING POINT OFTHE WAX FOR THE PURPOSE OF EXPANDING THE ENCASED WAX, WHICH COMPRISESPRE-HEATING THE WAX BEFORE ENCASEMENT TO TEMPERATURE EXCEEDING THEMELTING POINT OF THE WAX AND EXCEEDING THE MINIMUM TEMPERATURE REQUIREDTO EVOLVE HYDROCARBON GASES AND OXYGEN FROM THE WAX AND THEREBY FREEINGDISSOLVED HYDROCARBON GASES AND OXYGEN FROM THE WAX, MAINTAINING THEDEGASSED MOLTEN WAX UNDER VACUUM AND PREVENTING ABSORPTION OF OXYGEN,AND MOLDING THE MOLTEN DEGASSED WAX UNDER VACUUM INTO SOLIDIFIED UNITS,THEREBY PREVENTING GIVING OFF OF GASES AFTER ENCASEMENT WHEN THE ENCASEDWAX IS HEATED AND CONTRACTS BY COOLING.